"Arrow" has had an all around epic second season, and tonight it comes down to the biggest battle in the show's history. Who will come out on top: the heroes, led by Oliver Queen (Stephen Amell); or an army of super-powered villains, led by Slade Wilson (Manu Bennett)?

By the time the credits roll at 9 p.m. we'll know, one way or another. To find out what to expect from the season finale in advance, though, we talked to Andrew Kreisberg, the Executive Producer and writer of "Unthinkable."

MTV News: We're very excited about the season finale. From all of the promos, it seems like a small, intimate affair, not a lot of characters involved or anything like that.

Andrew Kreisberg: Exactly, exactly. All kidding aside, despite the large cast, and the biggest fight we've ever done, the biggest visual effects we've done, there really are a lot of small character moments, which I think differentiates "Arrow" from other action adventure TV shows. It does a lot of strong character work, or we hope it does a lot of strong character work.

It's more than just explosions, it's really about these people we've come to care about.

MTV: Given the footage we have seen, it seems like you've got this epic fight between Oliver's team, and Slade's army; but in the end it comes down to a moment between Oliver, Felicity and Slade. Are we headed towards something smaller, and gut-wrenching?

Kreisberg: It's got a little bit of everything. It's obviously got this big, giant fight… But I don't think anybody is going to be too surprised to find out that at the end of the day it's going to come down to The Arrow versus Slade, with the fate of the city and a few people's lives in the balance.

We actually open the episode with this epic montage, which could be titled "The Sad Ballad of Oliver Queen and Slade Wilson," to remind people this started early in season one. This episode is not just the culmination of this season, but also last season.

It really is, at the end of the day about these two men and the woman they both loved, and the anger that was unleashed from her death.

MTV: So what's it been like, taking a character like Slade who started as an ally and then making him an arch-villain who's almost destroyed an entire city?

Kreisberg: It's been fun, for the most part. It's always exciting to take a character people think they know and turn him on his head, and have people experience him in a whole new way. The best villains tend to have a personal connection to the hero. The fact that this was Oliver's friend, that Oliver is only alive right now because of Slade Wilson, because of the stuff Slade taught him on the island, how to survive the island, and the number of times he saved his life on the island.

In an odd way, Oliver owes Slade his life. And to have that be the person who is taking everything from you, and decimating your life bit by bit, life by life, it's that much more painful, because Oliver feels some measure of culpability in what's happening because he feels like he let Slade down.

The person it was most challenging for was Manu, because he throws himself with such gusto into everything he does. Manu and Selena, who plays Shado, and Stephen really had a fun Three Musketeers vibe on the island. And now, all of sudden they were having to kill each other, and scream and yell at each other. I think it was probably hardest on Manu, who was suddenly thrust into the role of villain.

MTV: The big season arc has been about whether Oliver is going to kill again, to become a murderer like he was in season one. I imagine we'll get an answer to that tonight, but whether he does, or doesn't… Is there a wrong choice?

Kreisberg: This season really was about Oliver deciding, "Can I be a hero if I'm also a killer?" That was the task he set out for himself at the beginning of the season, and that all comes to a head in this episode.

The choices that Oliver makes in the episode… That's partially where the title comes from. He's making some "Unthinkable" choices in this episode, that some people I'm sure will question, and debate about their merits.

Despite the explosions, and the fights, and the stunts, and the visual effects, watching Oliver wrestle with the decision to be a hero or a killer is the emotional core of the episode. That's what makes it so exciting.

MTV: I imagine it helped getting an early pick-up for season three, but when you're approaching a season finale like this how much is tying up what went on over the past twenty or so episodes, versus table-setting for next year?

Kreisberg: It's both. That's one of the aspects of the show that we're most proud of. It does feel like, to us that this is a satisfying conclusion to season two, while at the same time setting up season three.

In a way, they are sort of the same thing in this case, because this episode is about people making a choice, and really embracing a destiny for themselves. With Oliver, it's debating, "Am I a hero, or am I a killer?" For Thea, "Am I the daughter of Moira, or the daughter of Malcolm." For Sara, it's, "Am I the Black Canary, or am I a member of the League of Assassins?" For Roy, "Am I Thea's boyfriend, or am I part of Team Arrow?"

Everyone has a choice to make in this episode… And they make it. I imagine some people will be surprised at who chooses what, but in making those choices they are completing their arcs for season two, while letting the audience know, "Oh, now I know where this person will be heading for season three."

It wasn't a question so much of having to modulate between the two choices, between finishing season two, or starting season three, because they really in a lot of places were the same thing.

MTV: You mentioned Sara's decision… I know you guys have always said that being Black Canary was Laurel's destiny, but Sara certainly seemed to embrace the role this season -- and I imagine you guys have gotten somewhat attached to Caity Lotz. We had that flash of Laurel picking up a bow and arrow last episode, so is it possible that things have changed? Will Laurel not end up being Black Canary, with Sara taking the title?

Kreisberg: The answer to that question will be apparent 43 minutes after you start watching the finale. [Laughs]

"Arrow" airs Wednesday at 8 p.m. ET on The CW.